Glow discharge tube for emitting ultraviolet rays



Feb 5, 19356 H, L515 1,990,192

GLOW DISCHARGE TUBE FOR EMITTING ULTRAVIOLET RAYS Filed Oct. 5. 1931 Inventor v Hehdri K Lems,

( HIS Attorney.

Patented Feb. 5, 1935 UNITED STATES GLOW DISCHARGE TUBE FOR EMITTING ULTRAVIOLET nars Hendrik Lems, Eindhoven, Netherlands, assignor to General Electric Company, a corporation of New York Application October 5, 1931, Serial No. 566,88

In Germany October 9, 1930 3 Claims.

for the emission of ultraviolet rays. The wall of such tubes is made, at least partially, of a material transparent to. ultra-violet rays, for example of quartz and as a rule the tubes are provided with a filling of vapour, for example of mercury vapour. Some gas, for example a rare gas, is frequently added to the said filling of vapour. The ultraviolet rays generated by an electric discharge established in this vapour may pass throu'ghthe wall to the outside and be utilized for different purposes.

According to the invention, such a glow-discharge tube comprises one or more electrodes consisting of gauze so that the rays generated in the tube can easily pass to the outside. Besides, the metal, for example, the mercury, in the vapour of which the discharge has to be established is retained in small drops in the meshes of the gauze-shaped electrodes. When the tube starts operating, themetal is consequently rapidly heated so that very soon a vapour pressure of sufiicient value is obtained within the tube.-

A very favourable arrangement is obtained when the electrodes have the shape of concentric cylinders. Owing to this construction the I distribution of the electric field between the electrodes becomes very uniform, which is conductive to a uniiorm light distribution. The rays generated ma emerge from the tube in this case through thetineshes of the electrodes so that no trouble is e eriencedfrom these electrodes. In order that t e invention may be clearly understood and readily carried into eflect, it will be explained more fully with reference to the accompanying drawing which represents, by way of example, a glow-discharge tube according to the invention. In this drawing:

Figure 1 represents an elevation of this tube,

Figure 2 shows a section taken on the line 2-2, and Figure 3 is a perspective view of the tube.

The discharge tube represented in the drawing comprises a bulb 1 consisting of quartz and sealed by meansof some intermediary rings 2 to a stem or foot 3 of ordinary glass. The composition of the intermediary ringshas so been chosen, that the coefficient of expansion of the ring sealed to the quartz bulb 1 is only slightly greater than that of the quartz utilized whereas the coemcients of expansion of the other rings increase according as they are farther remote from the quartz.

The invention concerns glow-discharge tubes The foot 3 carries two electrodes 4 and 5 consisting of concentric cylinders made of'gauze. The tube contains some liquid mercury and,- in addition, some argon, for example, at a pressure of some millimetres has been introduced into the tube. For operating the discharge tube represented, a suitable tension is applied to the electrodes. The stabilizing resistance which has to be connected in series with the discharge path, may be housed, if desired, in the discharge tube or in the cap with which the tube may be provided. The cathode glow-discharge established between the electrodes 4 and 5 generates ultra-'- violet rays and which may pass to the outside through the quartz wall 1. It has been found that part of'the mercury is caught in the meshes of the gauze-shaped electrodes, which facilitates the production of a sufiiciently high pressure of the mercury vapour. The discharge tube represented is, for example, suitable for the production of ozone which is formed from the surrounding air by the ultra-violet rays of short wave-length.

What I claim is:

1. A gaseous electric glow discharge tube comprising an envelope, a gas filling therein comprising a vaporizable metal, a pair of electrodes therein so spaced as to have a cathode glow discharge passed therebetween, said electrodes consisting of concentric gauze cylinders to trap particles of the vaporizable metal and to facilitate the production of a high metal vapor pressure in said tube.

2. A gaseous electricglow'discharge tube com- Y 'therein'so spaced as to have a cathode glow discharge passed therebetween, the mesh of the said gauze electrodes being of a small size to trap drops of the vaporizable metal therein to facilitate the production of a high pressure ofrthe metal vapor in the device.

. HENDRIK LEMS. 

